Perindopril, (2S,3aS,7aS)-1-[(2S)-2-[[(1S)-1-(ethoxycarbonyl)butyl]amino]-1-oxopropyl]octahydro-1H-indole-2-carboxylic acid, is a compound effective for the treatment of hypertension and heart failure and it is marketed the United States as its tert-butylamine (or erbumine) salt under the commercial name Aceon®.
Perindopril and its pharmaceutically acceptable salts have important therapeutic properties. Their mode of action is to reduce or completely eliminate the activity of certain enzymes which are responsible, in some cases, for hypertension or cardiac insufficiency. In particular, perindopril inhibits the angiotensin-converting enzyme (ACE) thereby preventing the transformation of angiotensin I to angiotensin II. The hormone angiotensin II causes blood vessels to constrict which results in high blood pressure.
Pharmaceutically acceptable salts of perindopril which exhibits both good bioavailability and adequate stability for long term storage of the corresponding pharmaceutical compositions have been difficult to find. In particular The non-salt form of perindopril, as well as many salt forms, are unsuitable for long term storage due to liquefaction or decomposition of the compound.
U.S. Pat. No. 4,508,729 describes substituted imino-diacids, and more particularly to substituted azabicycloalkanedicarboxylic acids, their preparation and pharmaceutical compositions which contain them.
U.S. Pat. No. 6,696,481 describes the arginine salt of perindopril, its hydrates and also the pharmaceutical compositions comprising it. Also described is the salt of natural arginine (L-arginine).
WO 2007/099216 concerns a beta-crystalline form of formula (I), characterized by its X-ray powder diffraction diagram:

WO 2007/099217 relates to an alpha crystalline form of Formula (I), characterized by its X-ray powder diffraction diagram:
